Writing device, record carrier and method of writing information blocks, and reading device for reading information blocks

ABSTRACT

Reading a partly written writable record carrier having a track structure for positioning the write head above unwritten areas of the track pattern by means of a reading device which positions the read head on the basis of written marks, yields problems when an isolated information block after an unwritten area must be read. A system is disclosed for writing and reading information blocks on a record carrier of a writable type such as a CD-RW or a DVD-RAM. The writing device is provided with status means for generating status information which is indicative of the fact that at least one area of the record carrier has been written, while the status information comprises initial-area information which is indicative of an uninterrupted written initial area which extends from the start of a track pattern area intended for writing information blocks. The status information can be fixed on the record carrier. A reading device is also described, in which the positioning is dependent on the status information. Reading instructions with addresses outside the initial area can be rejected or translated via an address translation table into addresses in the initial area.

This application is a continuation of prior application Ser. No.10/376,201 filed Feb. 27, 2003, now U.S. Pat. No. 7616546 which is acontinuation of application Ser. No. 09/589,482 filed Jun. 7, 2000, nowU.S. Pat. No. 6,549,489 whis is a continuation of application Ser. No.08/972,756 filed Nov. 18, 1997, now U.S. Pat. No. 6,151,281 whichclaimed foreign priority of EP 96203218.1 filed Nov. 18, 1996 and EP96203285.0 filed Nov. 26, 1996 and EP 9720761 filed Mar. 14, 1997.

DESCRIPTION

The invention relates to a device for writing information blocks in atrack pattern on a record carrier of a writable type, which device isprovided with a write unit for writing areas of the record carrier via abeam of electromagnetic radiation with marks representing theinformation blocks, and positioning means for positioning the write uniton the record carrier on the basis of a track structure which isindicative of the track pattern.

The invention also relates to a writable record carrier having a trackpattern for writing information blocks, and a track structure which isindicative of the track pattern.

The invention also relates to a method of writing information blocks ina track pattern on a record carrier of a writable type, in which methodmarks representing the information blocks are written in areas of therecord carrier via a write unit and a beam of electromagnetic radiation,the write unit being positioned on the basis of a track structure whichis indicative of the track pattern.

The invention also relates to a reading device provided with read meansfor reading information blocks represented by optically readable marksin a track pattern on a record carrier, said device being provided witha read unit for reading the marks via a beam of electromagneticradiation, and positioning means for positioning the read unit on thebasis of the marks.

A writing device, a method and a record carrier of the type described inthe opening paragraph for writing information blocks are known from U.S.Pat. No. 4,901,300 (PHN 12.398). In the system described in thisdocument, information blocks are written in a track pattern on therecord carrier and represented by optically readable marks. The recordcarrier has a track structure in the form of a wobbling pregroove with avarying frequency which represents position information. The writingdevice has a write head for scanning the record carrier via a beam ofelectromagnetic radiation, with tracking signals being derived fromreflected radiation, and positioning means for positioning the writehead during scanning on the basis of the position information. Duringscanning, a modulation in the tracking signals is produced by thewobble. This modulation comprises the position information encodedtherein, indicating the absolute position in the track with respect tothe starting point of the area intended for information. The informationblocks are written on the record carrier at a desired position inconformity with their address, while, if necessary, the write head ispositioned via a jump in the track on the basis of the positioninformation. A record carrier may be partly written and then compriseswritten areas in which marks are present, and unwritten areas in whichonly the track structure is present. Reading devices are known whichderive the tracking signals and/or position information from the marks.A problem of these reading devices is that no position information canbe generated in unwritten areas, so that a partly written record carrieris not reliably readable.

It is an object of the invention to provide means with which a partlywritten record carrier can be read in a more reliable manner.

In accordance with a first aspect of the invention, a writing device asdescribed in the opening paragraph is therefore characterized in thatthe device is provided with status means for generating statusinformation which is indicative of the fact that at least one area ofthe record carrier has been written, the status information comprisinginitial-area information which is indicative of an uninterrupted writteninitial area which extends from the start of a track pattern areaintended for writing information blocks.

In accordance with a second aspect of the invention, a record carrier asdescribed in the opening paragraph is characterized in that the recordcarrier is provided with status information which is indicative of thefact that at least one area of the record carrier has been written, thestatus information comprising initial-area information which isindicative of an uninterrupted written initial area which extends fromthe start of a track pattern area intended for writing informationblocks.

In accordance with a third aspect of the invention, a method asdescribed in the opening paragraph is characterized in that statusinformation is generated which is indicative of the fact that at leastone area of the record carrier has been written, the status informationcomprising initial-area information which is indicative of anuninterrupted written initial area which extends from the start of atrack pattern area intended for writing information blocks.

In accordance with a fourth aspect of the invention, a reading device asdescribed in the opening paragraph is characterized in that thepositioning means are adapted to position in dependence upon statusinformation which is indicative of the fact that at least one area ofthe record carrier has been written, the status information comprisinginitial-area information which is indicative of an uninterrupted writteninitial area which extends from the start of a track pattern areaintended for writing information blocks.

The inventive measures have, inter alia, the advantage that the readingdevice only needs to be adapted in a limited way and does not need to beprovided with complex means for regaining position information on thebasis of the track structure.

An embodiment of the writing device according to the invention ischaracterized in that the device is provided with rewriting means forrewriting, contiguously to the initial area, information blocks whichare isolated from the initial area. This has the advantage that theisolated information blocks can be read with a simple, standard readingdevice because a copy is available within the initial area.

An embodiment of the reading device according to the invention ischaracterized in that the positioning means are adapted to rejectinstructions for positioning outside the initial area. This has theadvantage that the reading device prevents the read head from reachingan unwritten area whereby the reading device would come in an undefinedstate.

These and other aspects of the invention are apparent from and will beelucidated with reference to the embodiments described hereinafter.

In the drawings:

FIG. 1 shows a record carrier having a track structure,

FIG. 2 shows a partly written record carrier with status information,

FIG. 3 shows a partly written record carrier with rewritten informationblocks,

FIG. 4 shows a writing device for writing information blocks, and

FIG. 5 shows a reading device.

In the Figures, elements corresponding to those elements alreadydescribed have the same reference numerals.

FIG. 6 shows additional details of the positioner of FIG. 4.

FIG. 7 shows additional details of the system drive unit of FIG. 4.

FIG. 8 shows a network for implementing the invention.

FIG. 1 a shows a disc-shaped record carrier 1 having a track 9 intendedfor writing and a central aperture 10. The track 9 is arranged inaccordance with a spiral pattern of turns 3. The track 9 is indicated onthe record carrier by a track structure provided during manufacture ofthe blank record carrier. FIG. 1 b shows a cross-section taken on theline b-b of the record carrier 1, in which a transparent substrate 5 isprovided with a recording layer 6 and a protective layer 7. The trackstructure is constituted, for example by a pregroove 4 which enables awrite head to follow the track 9 during scanning. The pregroove 4 may beimplemented as an indentation or an elevation, or as a material propertydifferent from its surroundings. The track structure may also consist ofan alternation of elevated and deeper turns, referred to as land andgroove patterns, with a transition from land to groove or vice versataking place per turn. The recording layer 6 may be optically ormagneto-optically writable by means of a device for writing informationsuch as the known CD-Recordable. The information is organized ininformation blocks and is represented by optically readable marks in theform of a succession of areas reflecting large and small quantities ofradiation such as, for example a succession of pits of different lengthsin a CD. Such a writable disc is provided in the system of the novelhigh density optical disc, the Digital Versatile Disc (DVD) and isreferred to as DVD-RAM. FIGS. 1 c and 1 d show two examples of aperiodical modulation (wobble) of the pregroove. This wobble produces anextra signal in a tracking servorecorder. The wobble is, for examplefrequency-modulated and position information such as an address or atime code is encoded in the modulation. A writable CD system which isprovided with position information in this way is described in U.S. Pat.No. 4,901,300 (PHN 12.398) and U.S. Pat. No. 5,187,699 (PHQ 88.002). Atrack structure may also consist of, for example regularly dividedsub-patterns which periodically produce tracking signals. Other examplesof track structures are header symbols formed by optically readablemarks which are indicative of an address and indicate the initial areafor writing an information block. This description is based oninformation storage in a spiral track pattern which is filled from theinside outwards, for example as in a CD-ROM. The invention is alsoapplicable to other track patterns in which the turns are arrangedconcentrically instead of spirally, or to record carriers of differentshapes such as optical tapes.

FIG. 2 shows diagrammatically a partly written disc-shaped recordcarrier 1 provided with status information 25 according to theinvention. The area intended for information storage is indicated by anarrow 20 in a radial direction, the information being written from theinside outwards and the position information in the track structurecomprising, for example addresses ascending from the center. From thestart 26 of the area 20 intended for information storage, an initialarea 21 is uninterruptedly written with, for example a lead-in area,file management information and user information up to an end 24. Thefile management information comprises, for example directories and pathtables as known from ISO 9660. Moreover, second and third written areas22 and 23 are shown, which are isolated from the initial area 21 and areused for storing user information. It is true that the record carrier 1has a track structure as described with reference to FIG. 1, but in astandard reading device it is not usable for positioning when thestandard reading device derives the tracking and/or position informationon the basis of marks. The entirely written area 21 will be readable ineach reading device because marks are uninterruptedly present from aradius to be minimally used (for the relevant record carrier type).However, when such a standard reading device must read the isolatedareas 22 or 23, for example addressed via a read command, this devicewill displace a read head via a jump to a radial position correspondingto the address. However, since there are no marks, a standard devicewill not be able to position the read unit and reproduce no informationso that it may come in an undefined state. If the track structurecomprises headers which are formed by marks, the standard reading devicewill, in principle, be able to read them. However, due to the absence ofintermediate marks in unwritten areas, the read unit cannot bepositioned correctly above the track and tracking and read means cannotcorrectly respond. Consequently, reading of the headers in an unwrittenarea is unreliable. According to the invention, the record carrier isprovided with status information 25. This status information indicatesthat given areas on the record carrier are written and is stored in apredetermined way, for example in a given part of the lead-in area or inthe file management information. A reading device according to theinvention, as further described with reference to FIG. 5, can read andprocess the status information. The status information is furtherdescribed with reference to the writing device shown in FIG. 4. In theconventional types of rewritable optically readable record carriersprovided with phase-change material, the marks once written remainpresent and it is not common practice to use an erasing procedure torestore the record carrier to its blank, unwritten state again. If theinvention is used for a type of record carrier in which such an erasingprocedure is used, the status information should of course be adaptedaccordingly.

FIG. 3 a shows a partly written record carrier with rewritteninformation blocks in accordance with an embodiment of the invention. Inaddition to the written areas 21, 22, 23 shown in FIG. 2, areas 32 and33 are written contiguously to the initial area 21 after the end 24. Theinformation blocks recorded in the isolated areas 22 and 23 are writtenonce again in the contiguous areas 32 and 33. The sequence of theinformation blocks written once again can be freely chosen. In theconventional file management systems, the position of the informationblocks is indicated in the file management information. In a firstembodiment of the invention, the file management information is adaptedto the new location of the information blocks in the contiguous areas 32and 33. This has the advantage that the partly written record carriercan now be read by any standard reading device because all informationblocks are now located in the initial area and can thus be approachedvia an uninterrupted written area. In a practical embodiment, the statusinformation can be adapted by means of a reading/writing device such asa DVD-RAM drive, while the information blocks can be rewritten via asoftware program in a computer system connected to the DVD-RAM drive.This program can then be taken up in the device driver of the DVD-RAMinterface or used as a separate program, for example in the backgroundof a multitasking system. Rewriting can then take place when there areno other writing and/or reading instructions for the DVD-RAM drive. In afurther embodiment, the record carrier is provided with additionalposition information 35 at a predetermined position. This has theadvantage that the original file management information remainsunchanged. The additional position information then comprises, forexample an address translation table for translating the originaladdresses of the information blocks in the isolated areas 22 and 23 tothe new addresses of the rewritten blocks in the contiguous areas 32 and33. In the case of a reading instruction, a system drive in a readingdevice can read the address translation table and the status information25, and if the addresses to be read are outside the initial area 21, anaddress of the rewritten information block can be searched via theaddress translation table. In this case, it is an advantage that mostinformation blocks maintain their original address because, normally,the file management system positions the information blocks contiguouslyfrom the start. Consequently, only a relatively short addresstranslation table is required. In a practical embodiment, the addresstranslation table can be read and processed in a DVD drive or in theconnected computer system via device-driver software installed thereinin the conventional manner

FIG. 4 shows a device for writing information blocks on a disc-shapedrecord carrier of a writable type, for example magneto-optically oroptically (via phase change) writable via a beam of electromagneticradiation. During writing, marks representing the information are formedon the record carrier. The device is provided with drive means 45 forrotating the record carrier 1 and a write head 42 for scanning the trackwhich is indicated by the track structure on the record carrier. Thedevice is further provided with a system drive unit 46 for receivingcommands from a driving computer system or a user and for driving thedevice. To this end, the system drive unit comprises, for example amicroprocessor, a program memory and driver ports for performing theprocedures described hereinafter and for driving said elements. Thewrite head 42 is positioned radially on the track by positioning means44, detecting position information from the track structure. Inaccordance with known tracking and focusing methods, the write headscans the track while, for example, a modulation is present in thetracking signal due to the wobble in the pregroove. The tracking signalis demodulated and the position information encoded therein is regainedin the positioning means 44 and passed on the system drive unit 46. Theradial position of the write head can be verified via the regainedposition information. The information presented to the input of thewrite means 41 is divided, if necessary, into information blocks andconverted into a write signal for the write head 42. The write means 41comprise, for example an error encoder and a channel encoder. The systemdrive unit 46 drives the positioning means 44, the write means 41 andthe drive means 45 and is equipped to perform the procedures, to bedescribed hereinafter, for generating the status information.

The system drive unit 46 is adapted to detect whether areas are writtenand generate corresponding status information. This status informationis indicative of the fact whether at least one area of the recordcarrier is written, the status information comprising initial-areainformation which is indicative of an uninterrupted written initial areawhich extends from the start of a track pattern area intended forwriting information blocks. This initial area may be read by anystandard reading device, because no unwritten areas need to be crossedduring positioning. The status information 25 should only be adaptedwhen up to that moment blank, unwritten areas right after the end 24 arewritten. In a first embodiment, the initial-area information comprisesend-address information which is indicative of the position of the endof the initial area. The status information 25 in FIG. 2 then indicateswhere the end 24 of the initial area 21 is located, for example by meansof an address of the last written information block. It is to be notedthat it is not important whether the information block actuallycomprises information which is in use. The end address of the initialarea 21 then always indicates the highest, ever written end.Alternatively, the start and the length of the initial area can befixed, or the status of all relevant areas can be fixed in a bit map.The status of further areas located on the record carrier can be fixed,for example, as intervals in an interval table. When the initial areagrows at a given moment in such a way that it will be contiguous to aninterval already written, the limit of the initial area can be directlyshifted until after this interval. The interval table comprises intervalinformation which is indicative of the position of the start and end ofuninterrupted written areas of the track pattern. In another embodiment,the status of all sub-areas is fixed in a bit map. The statusinformation then comprises bit map information which is indicative ofwritten and unwritten areas. In this case, one bit is available for eacharea of a size to be minimally written in one run, while the bit of agiven address on the record carrier indicates the status. This minimalsize is dependent on the error correction used which extends across agiven quantity of information. For example, in a DVD, the size of aninformation block is 32 kbyte so that for 1 bit per information block abit map for 8 Gbytes fits in one information block. Also as an additionto the bit map, a table with written areas can be fixed in which atleast the end of the first written area (viewed in the radial directionfrom the central aperture) is given. Without an analysis of a largenumber of bits from the bit map, the size of the initial area can beread from this table.

In a first embodiment of the detection, the written state is derivedfrom the received writing instructions and possibly from successfullyperformed reading instructions. From the moment when the record carrieris introduced into the device, the system drive unit registers whichareas are written, for example, by means of a list of addresses or a bitmap as described above. In the case of a writing instruction for a givenaddress, the bit corresponding to this address is set to the state whichindicates the written state. In a second embodiment, the written stateis further detected because the system drive unit reads areas of therecord carrier on its own initiative. In another embodiment, the statusinformation is also derived from the file management information presenton the record carrier, which information conventionally comprises tablesstating whether addressable areas on the record carrier are free oroccupied. In this respect it is to be noted that this file managementinformation only indicates the current state, with no information beingpresent about areas written in the past and being meanwhile free again.In contrast, the status information also comprises information about allareas ever written which are meanwhile free again for new data storage.The system drive unit can store the status information of a given recordcarrier in a memory. Moreover, this stored status information may beprovided with an identification of the record carrier so that the statusinformation is available from the memory after the record carrier hasbeen re-inserted into the device.

In an embodiment of the writing device, the system drive unit fixes thestatus information on the record carrier itself. This has the advantagethat the status information is available at each drive in which therecord carrier is written. The status information can be fixed at apredetermined position on the record carrier, for example in orpreceding the lead-in area where no user information may be stored.Instead, the status information may be fixed as a file for which therules of the file management system used must be maintained (viaDirectories and Path Tables). The status information may be stored, forexample immediately after a change of the end of the initial area. Inone embodiment of the device, fixing on the record carrier is dependenton the operational circumstances. Fixing may be performed, for examplewhen no other writing instructions are available. It is also possible towait until a command is given to reject the record carrier from thedevice or to switch off the device. At that moment, the statusinformation must first be fixed. This has the advantage that wear due torepeated fixing can be limited. Fixing can also be postponed so that thestatus information is not written unnecessarily often but does not trailtoo much in the case of an unwanted interruption such as currentfailure. Thus it is possible to wait until at least N areas which havenot been written earlier are written since the last fixing procedure.When N is chosen to be, for example 16, at most 15 blocks more arewritten than the previous status information indicates. In an embodimentof the device, the system drive unit can supplement the fixed statusinformation, when the record carrier is re-inserted into the device, byreading information blocks contiguous to the initial area where at most15 blocks can follow. Moreover, the device can attempt to read smallunwritten areas, for example up to a length of 16 blocks and possiblyadapt the status information accordingly. If an uninterrupted areaseparated into two intervals by such a small area is incorrectly fixedin the status information, the status information can be adapted to oneinterval. Even if there appears to be a small gap between two writtenareas, the device may independently write this area with dummyinformation so that a better uninterrupted division is also obtained.

In a further embodiment, the above-mentioned operation is combined in a“paving” procedure. The gaps between the written areas are successivelywritten in the paving procedure described hereinafter by filling allgaps in consecutive work areas from the start of the track. FIG. 3 bshows diagrammatically three work areas on the record carrier 1 afterthe paving procedure has been completed, with the area from the start ofthe track being entirely written at least up to the radius of thefurthest outwardly located information block 23. A first work areaextends from the written area 21 to the radius 36 which is locatedfurther outwards. Subsequently, a second word area is indicated up to asecond further outward radius 37 and a last work area up to a thirdradius 38. The size of the work areas and hence their number is chosento be such that a work area can be filled in a limited period of time,for example one minute.

First, the system drive unit searches and reads the location of thetrack where the initial-area information such as the end address of theuninterrupted written initial area (End of Written Area, EWA) iswritten. When the record carrier is still completely unwritten or notpreviously submitted to the paving procedure, this location is stillunwritten and the location is initialized by recording the startingvalues such as, for example EWA=0. Secondly, a work area of apredetermined length just beyond the initial area is read for detectingthe status information in this work area. The length may be, forexample, 256 or 1024 information blocks and the status of each of theseblocks is subsequently known, namely whether they are written orunwritten. When, due to formatting of the information blocks, a givennumber of blocks should always be jointly written, only the status ofsuch a group needs to be determined. This is the case, for example, whenerror correction information is determined and written for a jointnumber of blocks. Moreover, bad sectors and verification can be takeninto account. Thirdly, the still unwritten gaps in this work area arefilled with dummy information, while areas which have already beenwritten are carefully skipped. Finally, the EWA is adapted to the newsituation, whereafter the uninterrupted written initial area is enlargedwith the work area. The paving procedure is then repeated for asubsequent work area. Alternatively, the EWA may be adapted after theenlargement with a number of small work areas; this has the advantagethat the location of the EWA needs to be rewritten less frequently. Itis to be noted that the EWA can be fixed with a resolution in conformitywith the minimal work area. Alternatively, the EWA may comprise theaddress of the block which was actually last written so that asubsequent paving procedure can start from EWA when the EWA value iswritten as the last value when an eject command breaks off theprocedure.

The above-mentioned paving procedure can be performed automatically whenthe operational circumstances allow this, for example when no externalinstructions have to be carried out. If another external instruction ispresented to the device during processing of the work area, theprocessing operation may be postponed or broken off completely. Afterthe external instruction has been carried out, the processing operationcan be resumed or restarted. In this case, of course the statusinformation within the work area should first be adapted to thesituation after the external instruction if, due to this instruction,sectors in the work area have been written. Alternatively, the pavingprocedure is started by an external instruction, for example a partialfinalization command when the user wants to make a DVD-RAM recordcarrier suitable for use in a DVD-ROM player. In this case, all gaps upto the highest address in use must be written with dummy information. Itis advantageous to write also a small area beyond the highest address inuse so that a DVD-ROM player which jumps a bit too far upon a jump tothis address does not land in an unwritten area. The highest address inuse may be derived, for example from the file management information orpassed along with the finalization command. The successive filling ofall gaps may be effected, for example in the manner describedhereinbefore by repeatedly processing work areas until the highestaddress in use is reached. Another full finalization command mayindicate that the complete record carrier is to be written up to thelimit of the area intended for storing information.

In a further embodiment, the status information comprises the value ofthe Last Used Block (LUB) which is fixed at a location on the recordcarrier, for example, together with the EWA. During a writinginstruction with a higher address than the LUB, this LUB is to beadapted. It is then advantageous to rewrite the LUB before performingthe writing instruction so that, in the case of current failure, thecorrect value for the LUB is present on the record carrier directlyafter performing the writing instruction. This causes some loss ofperformance because it is necessary to write at two locations in thecase of such writing instructions, which locations will be far apartfrom each other on the record carrier. In fact, the LUB will be fixedclose to the start of the track and, in contrast, the new informationblock to be written is far remote from the start of the track. It isadvantageous to fix only an indication of the Last Used Zone (LUZ)instead of the exact address of the Last Used Block, which zones may beas large as the work areas of the finalization procedure. Theperformance loss is now considerably limited because the LUZ only needsto be written once per zone when an information block must be writtenfor the first time in a zone which is located further outwards.

A further advantage is that the paving or finalization procedure as suchdoes not need to be fixed in a standard, except for the location of theEWA on the record carrier. In fact, it is not necessary that each deviceknows such a paving procedure and performs it in exactly the same way(for example, with a given size of the work areas), because the currentsituation of the area just beyond the EWA is always read first whenperforming the procedure. This precludes the risk that areas whichcomprise information are overwritten inadvertently.

In a further embodiment, several locations are reserved for statusinformation to be written on the record carrier. For predictablychanging parameters, such as EWA or LUZ, each new value will be higherthan the previous value. The new value is now fixed in a subsequentlocation, while the first value is re-used after use of the last value.During reading, all locations are read and the highest value isdetermined, i.e. the last written and, consequently, valid value. Thishas the advantage that wear due to repeated writing of one location isnow limited by the spread across all reserved locations. Alternatively,an (ascending) serial number can be written for a parameter to bewritten, by which the last fixed and hence valid parameter is known.

Dependent on the chosen way of fixing the status information, the systemdrive knows the location of the status information or a reference to thestatus information, or it uses the file management information in knownmanner so as to reproduce the status information. The status informationmay be fixed at a predetermined position on the record carrier, forexample in or preceding the lead-in area where no user information maybe stored. In contrast, another suitable position is near the end of thearea intended for data storage because, globally, the record carrierwill be filled from the start. When the area near the end is necessaryfor data storage when the record carrier has almost completely beenfilled, the status information will be limited to a small quantity ormay be canceled entirely because then there are (virtually) no unwrittenareas left. Instead, the status information can be fixed as a file. Inanother embodiment, for example extra validity information in the statusinformation may be stored on the record carrier. For performing a firstwriting instruction, the device writes the validity information on therecord carrier, indicating that the record carrier can comprise morewritten areas and/or areas which are in use than the status on thisrecord carrier indicates. If the operational circumstances permit this,a new version of the status is fixed, whereafter the validityinformation is fixed again as the last information but now with thecontents that the status is completely up to date. If the session isinterrupted in the meantime, for example, due to current failure ormanual removal of the record carrier, the validity information on therecord carrier indicates that the status information is incomplete.

A further embodiment of the writing device is provided with rewritingmeans for rewriting, contiguously to the initial area, informationblocks which are isolated from the initial area, as described withreference to FIG. 3 a. To this end, the system drive unit 46 is adaptedto detect isolated areas. Subsequently, the system drive unit will readthe block and write it once again, contiguously to the initial area butof course with an adaptation of the initial-area information in thestatus information. Moreover, the system drive unit is suitable foradapting the file management information or for taking up the originaladdress and the address after rewriting in an address translation table.In the case of a reading instruction from a driving computer system, theoriginal address will be derived from the file management information.The system drive unit will then translate this presented originaladdress into a physical address within the initial area via the addresstranslation table. In another embodiment, this translation can takeplace in the driving computer itself, which translation is then realizedby means of a software implementation, for example in device driversoftware. During rewriting, areas which are not written yet arepreferably used so that a maximal part of the record carrier is writtenand is therefore accessible to a standard reading device. If, at a laterinstant, an area in which a copy is written via the file managementinformation is put into use, the information block rewritten in thisarea should be rewritten again in an unwritten area located at a furtherposition but of course with a corresponding adaptation of the statusinformation. The system drive unit is adapted for this purpose andchecks, in the case of writing instructions in the initial area, whetheran area used for rewriting must be written. In that case, a newrewriting procedure is initiated, which proceeds in the manner describedpreviously with reference to FIG. 3 a in rewriting newly writtenisolated areas.

The temporary status information which has not been fixed yet ispreferably stored in a non-volatile memory in the writing device sothat, after termination of a current failure, the temporary statusinformation can as yet be fixed. In another embodiment, it can be fixedin the status information that the record carrier does not fully complywith the requirements of a reading device, for example when it is“partly ROM drive prepared” and possibly a list of information blocks tobe rewritten can be added. Moreover, a record carrier in which no areasare isolated because all isolated areas are rewritten can be marked assuch with “fully ROM drive prepared”. Furthermore, status informationcan be doubly fixed during storage so as to have a reserve copy of theseimportant data in the case of damage of the first storage area.

FIG. 5 shows a reading device according to the invention for readinginformation blocks. The reading device is provided with drive means 45for rotating the disc-shaped record carrier 1 and a read head 52 forscanning the track on the record carrier. The read head 52 is positionedradially on the track by positioning means 44 on the basis of signalsderived from marks on the record carrier. In accordance with theconventional Differential Phase Detection or Differential Time Detectionsystem (DPD or DTD), for example, the reflected radiation on a detector(not shown) can be collected, which detector is subdivided into 4sub-detectors. By determining phase or time differences between thesignals of the sub-detectors, the position of the scanning spot withrespect to the series of marks written in the track can be determined.In this respect it may be noted that such a device intended for readingRead-Only record carriers such as, for example DVD-ROM will not beprovided with means for deriving tracking and/or position informationfrom a track structure on a writable record carrier. During reading, thesignal of the read head 52 is converted into the information in the readmeans 43, for example comprising a channel decoder and an errorcorrector. Moreover, the device is provided with a system drive unit 46which, inter alia, on the basis of a read command, will displace theread head 52 to a radial position which is located a short distancebefore the area to be read (coarse positioning), and subsequently thesystem drive unit will derive the current position via the read head 52and the positioning means 44 from position information read from therecord carrier and subsequently (fine-)position the read head on thebasis of the position information. In the reading device according tothe invention, the positioning means are adapted to position independence upon the status information. When performing a jump, thepositioning means will then always position the read head above awritten part of the record carrier and then fine-position it via awritten area, if necessary, in a movement opposite to the direction ofthe jump. In an embodiment of the reading device according to theinvention, the positioning means are adapted to reject instructions forpositioning outside the initial area. This has the advantage that thedriving computer knows which instructions cannot be carried out andpossibly also why not via an error code in the rejection. Then, thereading device cannot come in an undefined state due to, for example anendless search for marks in an unwritten area. In a further embodimentof the reading device, the system drive unit 46 is adapted to translatethe original addresses from reading instructions to the physicaladdresses of the rewritten information blocks via the translation table,as described hereinbefore. The original address has then been determinedfrom, for example the file management information. If the originaladdress is located in the initial area, the information block has notbeen rewritten. Consequently, the translation only needs to take placeif the original address is indicative of a position outside the initialarea. In practice, the greater part of the information blocks will belocated in the initial area. This has the advantage that no translationis needed for a large number of reading instructions.

FIGS. 6 and 7 shows positioner 44 and system drive unit 46 of FIGS. 4and 5 in more detail. The purpose of this figure is to illustrate theclaimed apparatus and is not required for an understanding of theinvention. The apparatus and relationships shown in this figure has beenpreviously described in this specification, in relation to a specificembodiment of the invention, thus this portion of the description willonly briefly identify the apparatus.

In FIG. 6, positioner 44 includes apparatus 61 for positioning the readand write units; apparatus 62 for detecting position information on therecord carrier; apparatus 63 for controlling the position based on themarks on the record carrier and on the status information; and apparatus64 for rejecting instructions to read and/or write data outside of theinitial area. The positioner also includes an address translator fortranslating a first address of an information block in accordance withfile management information into a second address in the initial area.This allows reading from and/or writing to blocks of information whichhave been rewritten to copy the blocks to a position contiguous with theinitial area.

In FIG. 7, the system drive unit 46 includes a microprocessor 66,programmable memory 67 and ports 68 and 69 for receiving information andproviding control signals and information. Memory 67 includes programmedapparatus for controlling the operation of CPU 65 and a copy ofinformation that has been read or will be written to the record carrier,and other information required for operations. Programmed statusapparatus 70 includes apparatus 71 for generating status information 72including an indication 73 that at least one area of the record carrierhas been written and initial-area information 74 including end-addressinformation 75 indicating the position of the end of the initial area.The status information also includes an interval table 76 with intervalinformation 77 including information 78 indicating the start and end ofuninterrupted written areas. The status information also includesbit-map information 79 defining written and unwritten areas andincluding sub-area status information 105 and indication 106 of thestart and length of initial area.

Status apparatus 70 includes apparatus 80 to write status information 73onto the respective record carrier, and apparatus 81 to preserve andprocess the status information and write the status information to therespective record carrier depending on operational circumstancesincluding: apparatus 82 for fixing the status information when at leastN areas have been written since the last such fixing; apparatus 83 forwriting the status information when an eject command is received for therespective record carrier; apparatus 84 for writing the statusinformation when a command to turn off the device is received; andapparatus 85 for writing the status information when the end of theinitial area changes. The status apparatus also includes apparatus 86 todetermine the status information for a work area contiguous with theinitial area, and apparatus 87 for paving work areas (i.e. unwrittenparts contiguous with the initial area) with information to allowreliable tracking by writing into such work areas with dummyinformation. Finally the status apparatus includes apparatus 88 formaintaining a copy of the status information in memory, and apparatus 89for detecting written areas.

Memory 67 also includes programmed rewriting apparatus 90 includingapparatus 91 for rewriting to copy information blocks which are isolatedfrom the initial area to a position contiguous with the initial area.Rewriting apparatus 90 further includes: apparatus 92 for updating thefile management information 93 to indicate the new location ofinformation on the record carrier when areas are rewritten; apparatus 94for generating additional position information 95 including an addresstranslation table 96 with information 97 for translating a first addressof information blocks outside the initial area to a second address ofinformation blocks within the initial area, such as the original addressof isolated blocks to the new address of rewritten blocks; and apparatus98 for writing the address translation table to the respective recordcarrier. File management information 93 includes: a table 99 indicatingwhich areas are free and which areas are written; directories 100; andpath tables 101. The status information also includes a record carrieridentification 102 so that multiple record carriers may be used in thesystem.

The system of the invention may include an instruction rejectionapparatus 103 for rejecting instructions to read and/or write to thearea outside of the initial area to keep the system from going into anundefined state. The instruction rejection apparatus may be located inthe system drive unit as shown, or in the positioner as shown in FIG. 6,or in another portion of the system. In this specific embodiment, thesystem also includes apparatus 104 which uses the information in addresstranslation table 96, for translating an original address of informationblocks according to the file management information that are isolatedfrom the initial area into a new address of information blocks copied toa position contiguous with the initial area.

Memory 67 may be dynamic random access memory or non-volatile memory.The above specific embodiment with programmed devices may be implementedby reading programs and information from the record carrier 1 throughports 68 or 69, into memory 67. Alternatively the devices may beimplemented by connecting a memory component 107 to communicate with CPU66 such as by inserting a memory cartridge into a slot or a non-volatilememory package into a socket.

The reading and/or writing device of the invention may include aprogrammable computer system or computer network.

FIG. 8 shows computer system 110 and programmable computer system 111with a read and/or write unit 112, a read unit 113 and a positioner 114.communicating through a communications network 112. Computer 110includes apparatus 113 for programming computer 111 for implementing theinventions of this application. Computer 110 generates signalstransferred through communication network 114 to the programmablecomputer 111 to provide the programmed apparatus of the invention. Thusif the read or write unit is subsequently connected to computer 112,then the read device and/or write device of the invention will beimplemented, and the method of the invention practiced.

The invention has been disclosed with reference to specific preferredembodiments, to enable those skilled in the art to make and use theinvention, and to describe the best mode contemplated for carrying outthe invention. Those skilled in the art may modify or add to theseembodiments or provide other embodiments without departing from thespirit of the invention. Thus, the scope of the invention is onlylimited by the following claims

The invention may also be used for Write Once record carriers, such asCD-R or DVD-R. With the paving procedure described above, a partlywritten DVD-R may be rendered suitable for use in other reading devicesby filling up the unwritten areas with dummy information. In such arecord carrier, the paving or finalization procedure should of courseonly be started after an external command which may be given by the userif he does not want to store further information on the DVD-R.Parameters which are indicative of the written state, such as EWA, canbe stored in a memory in the device during the procedure and/or aftercompletion in the next free location of a series of locations reservedfor this purpose on the Write Once record carrier.

The invention claimed is:
 1. A device for writing information blocks ina track pattern on a record carrier of a writable type, which device isprovided with a write unit for writing areas of the record carrier via abeam of electromagnetic radiation with marks representing theinformation blocks, and positioning means for positioning the write uniton the record carrier on the basis of a track structure which indicatesthe track pattern, wherein the device is provided with status means forgenerating status information which indicates that at least one area ofthe record carrier has been written, the status information comprisinginitial-area information which indicates an uninterrupted writteninitial area.
 2. A device as claimed in claim 1, wherein theinitial-area information comprises end-address information whichindicates the position of the end of the initial area.
 3. A device asclaimed in claim 1, wherein the status information comprises intervalinformation which indicates the position of the start and the end of anuninterrupted written area of the track pattern.
 4. A device as claimedin claim 1, wherein the status information comprises bit map informationwhich indicates written and unwritten areas.
 5. A device as claimed inclaim 1, wherein the status means are adapted to fix the statusinformation on the record carrier.
 6. A device as claimed in claim 5,wherein the status means are adapted to preserve and process the statusinformation during a period and to fix said information after the periodin dependence upon operational circumstances.
 7. A device as claimed inclaim 6, wherein the operational circumstances comprise writing of atleast N areas not previously written since fixing the last information,a command to eject the record carrier from the device or a command toswitch off the device.
 8. A device as claimed in claim 1, wherein thestatus means are adapted to determine the status information in a workarea contiguous to the initial area and to write the unwritten parts ofthe work area with dummy information.
 9. A device as claimed in claim 1,wherein the device is provided with rewriting means for rewriting,contiguously to the initial area, information blocks which are isolatedfrom the initial area.
 10. A device as claimed in claim 9, wherein therewriting means are arranged to adapt file management informationindicating the position of the information blocks on the record carrierto the position of the rewritten information blocks.
 11. A device asclaimed in claim 9, wherein the rewriting means are adapted to generatean address translation table on the record carrier, which addresstranslation table comprises information for translating the originaladdress of rewritten information blocks into the address after therewriting operation.
 12. A writable record carrier having a trackpattern for writing information blocks, and a track structure thatindicates the position of the track pattern, wherein the record carrieris provided with status information which indicates the fact that atleast one area of the record carrier has been written, the statusinformation comprising initial-area information which indicates anuninterrupted written initial area.
 13. A record carrier as claimed inclaim 12, wherein the status information comprises an addresstranslation table which comprises information for translating a firstaddress of information blocks in accordance with file managementinformation into a second address in the initial area.
 14. A method ofwriting information blocks in a track pattern on a record carrier of awritable type, in which method marks representing the information blocksare written in areas of the record carrier via a write unit and a beamof electromagnetic radiation, the write unit being positioned on thebasis of a track structure which indicates the position of the trackpattern, wherein status information is generated which indicates thefact that at least one area of the record carrier has been written, thestatus information comprising initial-area information which indicatesthe position of an uninterrupted written initial area.
 15. A readingdevice comprising: read means for reading information blocks representedby optically readable marks in a track pattern on a record carrier, aread unit for reading the marks via a beam of electromagnetic radiation,and positioning means for positioning the read unit on the basis of themarks, wherein the positioning means are adapted to position dependingon status information which indicates that at least one area of therecord carrier has been written, the status information comprisinginitial-area information which indicates the position of anuninterrupted written initial area.
 16. A reading device as claimed inclaim 15, wherein the positioning means are adapted to rejectinstructions for positioning outside the initial area.
 17. A readingdevice as claimed in claim 15, wherein the reading device is providedwith translation means for translating, in dependence upon an addresstranslation table, a first address of information blocks in accordancewith file management information into a second address in the initialarea, in case the first address indicates a position outside the initialarea.
 18. The device of claim 1 wherein the uninterrupted written areaextends from the start of a track pattern area for writing informationblocks.
 19. The record carrier of claim 12 wherein the uninterruptedwritten area extends from the start of a track pattern area for writinginformation blocks.
 20. The method of claim 14 wherein the uninterruptedwritten area extends from the start of a track pattern area for writinginformation blocks.
 21. The reading device of claim 15 wherein theuninterrupted written area extends from the start of a track patternarea for writing information blocks.
 22. A device for writinginformation blocks in a track pattern on a record carrier of a writabletype, the device comprising: a write unit for writing areas of therecord carrier via a beam of electromagnetic radiation with marksrepresenting the information blocks, positioning means for positioningthe write unit on the record carrier on the basis of a track structurewhich indicates the track pattern, status means for generating statusinformation which indicates that at least one area of the record carrierhas been written, the status information comprising initial-areainformation which indicates an uninterrupted written initial area whichextends from the start of a track pattern area for writing informationblocks, the status means are for determining the status information in awork area contiguous to the initial area and to write the unwrittenparts of the work area with dummy information.
 23. The device of claim22, wherein the initial-area information comprises end-addressinformation for indicating the position of the end of the initial area.24. The device of claim 22, wherein the status information comprisesinterval information for indicating the position of the start and theend of an uninterrupted written area of the track pattern.
 25. Thedevice of claim 22, wherein the status information comprises bit mapinformation for indicating written and unwritten areas.
 26. The deviceof claim 22, wherein the status means fixing the status information onthe record carrier.
 27. The device of claim 26, wherein the status meansare for preserving and processing the status information during a periodand to fix said information after the period depending upon operationalcircumstances.
 28. The device of claim 27, wherein the operationalcircumstances comprise one of more of: writing of at least one areas notpreviously written since fixing the last information, a command to ejectthe record carrier from the device, and a command to switch off thedevice.
 29. The device of claim 22, comprising rewriting means forrewriting, contiguously to the initial area, information blocks whichare isolated from the initial area.
 30. The device of claim 29, whereinrewriting means are for adopting file management information indicatingthe position of the information blocks on the record carrier to theposition of the rewritten information blocks.
 31. The device of claim29, wherein the rewriting means are for generating an addresstranslation table on the record carrier, which address translation tablecomprises information for translating the original address of rewritteninformation blocks into the address after the rewriting information. 32.A writable record carrier having track pattern for writing informationblocks, and a track structure which indicates the track pattern, saidrecord carrier comprising: status information which indicates that atleast one area of the record carrier has been written, the statusinformation comprising initial-area information which indicates anuninterrupted written initial area which extends from the start of atrack pattern area for writing information blocks, the statusinformation comprising interval information indicating the position ofthe start and the end of uninterrupted written areas of the trackpattern.
 33. The record carrier of claim 32, wherein the statusinformation comprises bit map information for indicating written andunwritten areas.
 34. The record carrier of claim 32, wherein the statusinformation comprises an address translation table which comprisesinformation for translating a first address of information blocks inaccordance with file management information into a second address in theinitial area.
 35. A method of writing information blocks in a trackpattern on a record carrier of a writable type, in which method marksrepresenting the information blocks are written in areas of the recordcarrier via a write unit and a beam of electromagnetic radiation, thewrite unit being positioned on the basis of a track structure whichindicates the track pattern, said method comprising the acts of:generating status information which indicates that at least one area ofthe record carrier has been written, the status information comprisinginitial-area information which indicates an uninterrupted writteninitial area which extends from the start of a track pattern areaintended for writing information blocks; determining the statusinformation in a work area contiguous to the initial area; writing theunwritten parts of the work area with dummy information.
 36. The methodof claim 35, wherein the step of generating the status informationcomprises a sub-step of generating bit map information for indicatingwritten and unwritten areas.
 37. A reading device provided with readmeans for reading information blocks represented by optically readablemarks in a track pattern on a record carrier, said reading devicecomprising: a read unit for reading the marks via a beam ofelectromagnetic radiation, positioning means for positioning the readunit on the basis of the marks depending upon status information whichindicates that at least one area of the record carrier has been written,the status information comprising initial-area information whichindicates an uninterrupted written initial area which extends from thestart of a track pattern area for writing information blocks wherein thepositioning means are for rejecting instructions for positioning outsidethe initial area.
 38. The reading device of claim 37, comprising:translation means for translating, depending upon an address translationtable, a first address of information blocks in accordance with filemanagement information into a second address in the initial area, incase the first address indicates a position outside the initial area.39. A device for writing information blocks in a track pattern on arecord carrier of a writable type, which device is provided with a writeunit for writing ares of the record carrier via a beam ofelectromagnetic radiation with marks representing the informationblocks, and positioning means for positioning the write unit on therecord carrier on the basis of a track structure which indicates thetrack pattern, wherein the device is provided with status means forgenerating status information which indicates that at least one area ofthe record carrier has been written, the status information comprisinginitial-area information which indicates an uninterrupted writteninitial area, wherein the status means are adapted to determine thestatus information in a work area contiguous to the initial area and towrite the unwritten parts of the work area with dummy information.
 40. Adevice for writing information blocks in a track pattern on a recordcarrier of a writable type, which device is provided with a write unitfor writing areas of the record carrier via a beam of electromagneticradiation with marks representing the information blocks, andpositioning means for positioning the write unit on the record carrieron the basis of a track structure which indicates the track pattern,wherein the device is provided with status means for generating statusinformation which indicates that at least one area of the record carrierhas been written, the status information comprising intial-areainformation which indicated an uninterrupted written initial area,wherein the sequence in which the device writes information blocks onthe record carrier may be freely chosen.